pause sync when app is backgrounded

gomuks

@@ -1 +1 @@
-Subproject commit 7e43a63e578b0d6f52269d65297198077bf5b45d
+Subproject commit ba82b6e31c87c99766a8366a72a9f07d643b323f

lib/controllers/app_paused.dart

@@ -0,0 +1,18 @@
+import "package:flutter/widgets.dart";
+import "package:flutter_riverpod/flutter_riverpod.dart";
+
+class AppPausedController extends Notifier<bool> {
+  @override
+  bool build() {
+    final listener = AppLifecycleListener(
+      onPause: () => state = true,
+      onResume: () => state = false,
+    );
+    ref.onDispose(listener.dispose);
+    return WidgetsBinding.instance.lifecycleState == .paused;
+  }
+
+  static final provider = NotifierProvider<AppPausedController, bool>(
+    AppPausedController.new,
+  );
+}

lib/controllers/client.dart

@@ -95,6 +95,11 @@ class ClientController extends AsyncNotifier<int> {
       }
     });
 
+    if (!ref.mounted) {
+      GomuksDestroy(handle);
+      return Completer<int>().future;
+    }
+
     ref.onDispose(() => GomuksDestroy(handle));
 
     return handle;

lib/controllers/gomuks_listener.dart

@@ -1,10 +1,12 @@
 import "dart:async";
 import "dart:ffi";
+import "dart:io";
 import "dart:isolate";
 
 import "package:fast_immutable_collections/fast_immutable_collections.dart";
 import "package:flutter/foundation.dart";
 import "package:nexus/controllers/account_data.dart";
+import "package:nexus/controllers/app_paused.dart";
 import "package:nexus/controllers/client.dart";
 import "package:nexus/controllers/client_state.dart";
 import "package:nexus/controllers/init_complete.dart";
@@ -141,6 +143,20 @@ class GomuksListenerController extends AsyncNotifier<void> {
     if (errorCode != 0) {
       throw Exception("GomuksStart returned error code $errorCode");
     }
+
+    if (!ref.mounted) return;
+
+    if (Platform.isAndroid || Platform.isIOS) {
+      // Mobile OSes block network access for backgrounded apps, so pause
+      // syncing instead of letting it fail.
+      ref.listen(AppPausedController.provider, (_, paused) {
+        if (paused) {
+          GomuksPauseSync(handle);
+        } else {
+          GomuksResumeSync(handle);
+        }
+      }, fireImmediately: true);
+    }
   }
 
   /// Waits for gomuks to report the client's device ID